Organic zinc and manganese enhance eggshell ultrastructure by influencing its calcium deposition to improve eggshell quality in laying hens

Abstract Background This study aimed to explore the mechanism of organic zinc and manganese (OZM) influencing eggshell quality of laying hens. A total of 384 21‐week‐old Jingfen‐1 laying hens were randomly divided into four groups (8 replicates per group, 12 hens per replicate): control group (60 mg kg −1 Zn as zinc sulfate and 80 mg kg −1 Mn as manganese sulfate) and OZM groups (5, 10 and 15 mg kg −1 Zn as yeast zinc and 80 mg kg −1 Mn as manganese methionine). Results Compared with the control group, OZM_5 and OZM_10 groups significantly increased feed intake and egg weight in laying hens in 28–31 weeks ( P < 0.05) while egg weight and shell weight were increased in all the OZM groups ( P < 0.05). In addition, the OZM_15 group significantly decreased the mammillary knob width and mammillary layer thickness and increased the palisade layer thickness and total effective thickness ( P < 0.05), and had a stronger and more stable Ca signal strength in the mammillary layer and a more uniform and dense distribution of calcium and zinc in the transversal surfaces of eggshell. Furthermore, mRNA levels of Claudin2 , Zona Occludens 1 , Alkaline phosphatase and Ca 2+ ATPase were significantly upregulated in the OZM_15 group of laying hens at week 31 ( P < 0.05). Conclusion Dietary supplementation of 10–15 mg kg −1 yeast zinc and 80 mg kg −1 manganese methionine can enhance eggshell ultrastructure by influencing its endometrial barrier function and calcium deposition, thereby improving eggshell quality. © 2024 Society of Chemical Industry.